Measuring about 210 square kilometers, surrounded by the Indian Ocean and about 2.5 km south of Cilacap. Most of the island is still covered by jungles, home to a variety of wild animals.

In 1934, the island was first established as a penal island by the Departement van Recht en Justitie, or Justice Ministry under the Dutch colonial government.

The Dutch prepared the island as a penal island, similar to Alcatraz at the San Fransisco Bay, USA. The